This invention relates to a mixture of a vinyl aromatic-diene block copolymer rubber and a nitrile barrier resin, and to the use of this mixture as a tie-layer to adhere together a nitrile barrier resin and a thermoplastic resin. Optionally, these tie-layers contain additional thermoplastic resins.
Composite structures composed of at least one layer of a thermoplastic resin and at least one layer of a nitrile barrier resin have been prepared and are found to be useful for many purposes, primarily for packaging. Packages of such composites have excellent gas barrier properties, particularly for oxygen and carbon dioxide. Manufacture of such composites is not easy because of the lack of adhesion between the surfaces of most thermoplastic resins and a nitrile barrier resin. This lack of adhesion has been improved in the past by the discovery of new adhesives such as those disclosed in U.S. Pat. No. 4,123,576.
One problem with many of the prior art adhesives is that they have very poor processability. The adhesives disclosed herein have excellent processability. Moreover, an additional advantage of the instant adhesives is that scrap material can be reground and used in the tie-layer with a minimum adjustment of the essential components.